Gas Laws SPS5b: Relate temperature, pressure, and volume of gases to the behavior of gases.

Characteristics of Gases There is a lot of “free” space in a gas Expand to fill their container They can be expanded infinitely Can be compressed Are fluids (like liquids) Have very low densities Diffuse and mix rapidly

Pressure Pressure = Force Area Measured in kilopascals (kPa) or atmospheres (atm)

Standard Temperature and Pressure (STP) Defined as: 0ºC and 1 atm Absolute zero – temperature at which the volume of a gas would equal zero.

P T V Gas Laws Pencil Trick! The three important measurements when we talk about Gas Laws are: P-Pressure T-Temperature V- Volume We can illustrate how they are related using a pencil with labels. P T V

Gas Laws Boyle’s Law – the pressure and volume of a gas are inversely proportional. Temperature is kept constant. Pressure Volume

Boyle’s Law in Real Life Carbonation: Water and syrup mixture is pumped full of carbon dioxide gas and you have soda pop. When a soda bottle is filled, it is also pressurized. When you slowly open the cap, the gas is suddenly able to increase its volume in order to decrease the pressure. Since the soda itself is carbonized, the CO2 gasses decide they want to escape as well, and you have your fizz.

Gas Laws Charles’s Law – the volume and temperature of a gas are directly proportional. Pressure is kept constant. Temperature Volume

Charles’s Law in Real Life Hot Air Balloon: Gases expand when they are heated. Particles in the hot air are farther apart than in the cool air, so the hot air is less dense. The less dense hot air rises along with the balloon and the basket.

Gas Laws Gay-Lussac’s Law - the pressure and temperature are directly related. Volume is kept constant. Temperature Pressure

Amonton’s Law in Real Life Hot vs. Cold Tire Pressure: Gases expand when they are heated. When the gases expand in a tire that has a constant volume, the pressure increases. The tire pressure of a cold tire is lower than the tire pressure of the same tire after a long drive.

Phase Change Diagram Tells you what phase of matter a substance will be in at a certain temperature and pressure. A substance’s boiling point and freezing/melting point can vary if the pressure changes. Standard melting and boiling points are done at Standard Pressure (1 atm).

Phase Change Diagram Triple Point - The temperature and pressure at which the solid, liquid, and gas phases exist simultaneously. Critical Point - The temperature above which a substance will always be a gas regardless of the pressure.

PRACTICE! What state of matter would the substance be at 31°C and a pressure of 1 atm? At what temperature and pressure would the substance exist as a solid, liquid, and a gas at the same time?